Continuous measurements of aerosol properties at the Baltic Sea

Thirty months (March 2003–October 2005) of aerosol size distributions, trace gas and meteorological parameter measurements have been analysed at a background station in Baltic Sea. Log-normal modes have been fitted to the size distributions and a source region analysis using 120 h back trajectories has been accomplished. Seasonal and air mass influences have been studied and compared to other measurement sites. Only weak impacts of meteorological conditions have been found. New particle formation events were observed, but less frequently compared to continental sites, which is concluded being related to the lack of precursor gas sources close to the station and a higher condensation sink. The northeast Atlantic was recognized as an important source of particles in the Aitken mode. Especially in spring and summer, probably primary biogenic particles contribute largely to the particle number concentration. Source regions of the submicron aerosol are strongly dependant of the particle size and so is the contribution to the total number or mass concentration. For this reason, a consideration of the total number or mass concentration was identified not being sufficient in order to describe source areas of aerosol particles.